Why jQuery removes Margin when showing/hiding the element?

Why jQuery removes Margin when showing/hiding the element?

I have an element that has margin-top and border. When I call $(element).show() it doesn't use the element's margin and the it doesn't look good (in original fiddle If you click on the div that is after the input text the slide animate starts from top of the text input and you see a black line passing it and it's not beautiful! I want the animate start form the bottom of the text input.)

This is my beta in jsFiddle. but The orginal is diffrent (I remove an element because the wanted element cannot be found!)

Can anybody help me?